This invention relates to the use of ultrasonic sound for locating foreign particles in an object and more particularly, but not by way of limitation, to a method of determing foreign materials in food products such as meat, poultry, fish and other products which are susceptible to receiving foreign particles therein before the food products are packed for storage and shipment.
Heretofore, ultrasonic sound frequency using transducers has been greatly used in non-destructive testing and in particular, for determining metallurgical flaws in alloys, weld joints, castings, and other metal materials. Also transducers have been used in rotating tires, balloons, or diaphrams having liquid copulants therein. Specifically, these types of test devices are disclosed in U.S. Pat. No. 2,545,101 to Meunier, U.S. Pat. No. 3,507,308 to White, and U.S. Pat. No. 4,098,132 to Mikesell. Also recent patents have issued using various types of ultrasonic transducers in U.S. Pat. Nos. 4,096,755, 4,096,757, 4,092,868, 4,096,736, 4,098,129 and 4,099,045.
None of the prior art inventions using ultrasonic sound specifically deal with the problem of foreign material in food products and finding the contaminated food product prior to packaging and shipment to the consumer.
The food processing industry has grown rapidly in the recent years due to a growing population and in particular, food products for fast food franchises. Because of the large demand of various types of food products such as meat products, hamburger patties, fish fillets, boneless chicken products, boneless fish products, and the like, a growing concern by the food processing company has been brought about because of potential product liability when foreign material is found by the consumers in their food purchase.
Prior to the subject invention foreign particles were detected in food products on assembly lines and conveyor belts by visual inspection. Visual inspection has been ineffective when foreign particles cannot be seen visually on the surface of the food product or when the inspector is negligent and fails to view the products carefully.
The subject invention provides a method of determining foreign material in food products and automatically rejecting the contaminated food products from the conveyor or processing line.